Using ActionView helpers elsewhere

I am working on a reporting library (perhaps a gem someday). It's
coming along pretty well thus far, though I could use some collective
intelligence on something.

I would like ActionView::Base (particularly the helpers to be
available within a lambda. The point of this is to define
transformations on columns (0..n) within an instance of the class to
output within an erb template.

For reference, both class A and B below produce the correct result,
but class C is what I'm trying to do.

class A < ActionView::Base
  def run
    content_tag('a','b')
  end
end

class B < ActionView::Base
  def run
    l = lambda { content_tag('a','b') }
    l.call
  end
end

class C < ActionView::Base
  attr_accessor :l

  def run
    l.call
  end
end

a = A.new
=> #<A:0xb35c9a00 @controller=nil, @assigns_added=nil, @assigns={},
@view_paths=[], @logger=nil>
a.run
=> "<a>b</a>"

b = B.new
=> #<B:0xb35c60f8 @controller=nil, @assigns_added=nil, @assigns={},
@view_paths=[], @logger=nil>
b.run
=> "<a>b</a>"

c = C.new
=> #<C:0xb35c37b8 @controller=nil, @assigns_added=nil, @assigns={},
@view_paths=[], @logger=nil>
c.l = lambda { content_tag('a','b') }
=> #<Proc:0xb35bf938@(irb):26>
c.run
NoMethodError: undefined method `content_tag' for #<Object:0xb7d249a4>
        from (irb):26
        from (irb):18:in `call'
        from (irb):18:in `run'
        from (irb):27

Any thoughts?